1. Technical Field
The present invention is directed toward aeration of particulate material, and more particularly toward an apparatus for aerating particulate material such as compost.
2. Background Art
Increasing waste production and decreasing capacity for waste disposal has led to exploration of alternatives for conventional landfilling of waste. The ability to compost organic waste to reduce the volume of waste and produce a usable byproduct has led to expansion of the composting industry.
One known method and apparatus for composting is disclosed in Allen, U.S. Pat. No. 6,099,613 (the “Cedar Grove patent”), the contents of which are incorporated herein in their entirety. The Cedar Grove patent is directed to a composting system and apparatus using pavement as a bearing surface for piles of particulate composting material. A plurality of ventilation conduits underlie the pavement surface and a plurality of delivery conduits extend between the ventilation conduit and the pavement surface to provide aeration to particulate composting material deployed on the pavement surface. The Cedar Grove patent recognizes the need to provide a grate covering the delivery conduits. In order to protect the grate from equipment used to move composting material on the pavement surface, it teaches recessing the grates below the pavement surface about 2-5 inches. It further teaches providing openings in the grates sized to prevent rocks and other debris from entering the delivery conduits.
In practice, debris gets packed into the recess overlying the grates and significantly inhibits the flow of air through the grates, thus diminishing efficient composting. In order to handle denser, wetter feed stocks, the Cedar Grove system requires disposable tees to be installed loosely over each recessed air grate. The cost of the tees as well as the time and effort required to place and replace the tees in the recess increases the cost of this composting system.
Finn, U.S. Pat. No. 5,758,482, is directed to an air floor grating system for use in curing compost. Finn teaches a system having elongate air channels that are covered with elongate grates having a top surface at about the level of a bearing surface of the compost curing system. The grates of the Finn system feature air passages which are intended not to plug under traffic by rubber-tired vehicles used for manipulating the compost. More particularly, the openings of the Finn system features a narrow slot at the top surface which tapers to a wider opening at the bottom of the grate. The design is intended to ensure that compost entering the slot does not plug the opening, but falls through the opening and into the trench below to provide a self-cleaning unit.
The system of Finn relies on easy access to the underlying air channels to provide cleaning and removal of material falling into the air channels through the grates. Another problem with the system of Finn involves accidental displacement of the grates. This allows a large volume of material to enter the air channels and disrupts a uniform air flow. Also, the small slits described in Finn (0.05-0.063 inch at the surface) cannot accommodate high moisture conditions that cause hydraulic swelling of smaller organic matter particles. In addition, the linear system of Finn is subject to non-uniform air flow from one end of an air channel to another in the event of displacement of a grate or varying back pressures caused by non-uniform distribution of composting material over the grates.
The present invention is intended to overcome one or more of the problems discussed above.